1. Field of the Invention
The present invention relates to a technique for managing user information when exchanging a message between users on a network.
2. Description of the Related Art
There is conventionally known network communication tools that are used to exchange a message between users of client machines connected to a network, typically the Internet. One of such network communication tools is a tool for performing a message exchange between two users in real time on the Internet by unicast (one-to-one communication). For example, there is a two-sided message exchange tool in multiwindow environments as in ICQ (trademark of Milabilis in Israel). The two-sided message exchange tool is one in which the client machines display a transmission message and a reception message respectively to make it possible to perform a message exchange between two sides in a message exchange system in which client machines are connected to an ICQ server.
Each user of such a two-side message exchange tool holds a list in the message exchange system. The list has preregistered information of at least-one user such as friends etc. with whom each user wishes to perform message exchange.
There is a system that requires acceptance from a user desired to be registered when one user of the two-side message exchange tool register& information of the other user to the list. A first user registers information of a second user into the first user's list based on acceptance from the second user. Similarly, the second user registers information of the first user to the second user's list based on acceptance from the first user. The first user cannot register information of the second user in the first user's list Without obtaining the acceptance from the second user.
However, in the case where two users mutually register their information in their lists to use the two-side message exchange tool, even when the first user deletes information of the second user from the first user's list for personal reasons, the second user is not informed that information of the second user has been deleted from the first user's list. The second user recognizes that mutual registration with the first user is continued.
If information of the first user stays registered in the second user's list in spite of the absence of registration information of the second user in the first user's list, there is a possibility that trouble will occurs in consistency of two-side message exchanges. There is a problem in which the first user cannot protect privacy since information of the first user stays registered in the second user's list against the first user's will.
In the system that requires acceptance from a user desired to be registered when one user registers information of the other user in the aforementioned list, the first user must register information of the second user to the first user's list based on acceptance from the second user. Similarly, the second user must register information of the first user to the second user's list based on the acceptance from the first user. This causes a problem in which the mutual registration procedure becomes complicated when two users mutually register their information in their lists.
There is a case in which the second user cannot obtain acceptance from the first user in spite of the fact that the first user registers information of the second user in the first user's list based on acceptance from the second user. In this case, the second user cannot register information of the first user in the second user's list. Namely, information of the second user stays registered in the first user's list in a one-sided manner. This causes a problem in which imbalance will occur in view of protection of privacy.